Determination of 22 preservative residues in citrus by UPLC-MS/MS with multiple ion reaction monitoring

A method for determining residues of 22 preservative in citrus by ultra-high performance liquid chromatography-tandem mass spectrometry（UPLC-MS/MS）was established．Samples were extrated by QuEChERS method, separated on an UPLC BEH C18 column, eluted with mobile phase of 0.01% formic acid in water and 0.01% formic acid in methanol．Target compounds were detected under multiple reaction monitoring（MRM）mode with an electrospray ionization positive ion source．Quantification was performed using an external standard method．Results showed that 22 preservatives exhibited good linearity（correlation coefficient >0.997）across concentrations ranging within 5～200 μg/L, method detection limits ranged within 0.10～0.60 μg/kg．Spiked recovery rates at addition levels of 10, 20, and 100 μ g/kg ranged within 86.3%～116.6%, with relative standard deviations（n=6）within 0.6% ～4.8%．By using multiple ion reactions to monitor ion abundance ratio of target compounds, all detected samples were confirmed as positive．This method has advantages of simple operation, highly sensitive, and good reproducibility, making it suitable for simultaneous determination of 22 preservative residues in citrus．